'99 LS1 AF Ratio
Thread Starter
Le Mans Master
Joined: Jan 2002
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From: Kyle TX (Because Mojo Made me fill it in)
'99 LS1 AF Ratio
Im trying to learn more about the LS1 engines. Is it normal for a LS1 to read about 12.5 at 1900 rpm and 12.1 at 5800 rpm on a dyno? The avg across the board is 12.3.
Thread Starter
Le Mans Master
Joined: Jan 2002
Posts: 5,320
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From: Kyle TX (Because Mojo Made me fill it in)
Originally Posted by Mike Mercury
I've always understood that 12.6 : 1 is the optimum WOT AF ratio for non-blown engines on dyno (12.9 :1 on the street).
so your 12.3 is very close to optimum.
so your 12.3 is very close to optimum.
So you dont think the 12.1 at the upper rpm range should be closer to 12.5 or 12.6? Just curious since on my 86 I was always told to keep it flat at 12.7 across the board and my LS1 gets a little richer as the rpm climbs.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I will be purchasing some tuning software SOON and I have got to learn all of this tuning stuff so I can get my car to run better. Is there a LS1 Edit or HP tuners forum or website for dummies??? 
I wached my tuner manipulate all of my PCM data but it was a BLUR!!!
BC
I wached my tuner manipulate all of my PCM data but it was a BLUR!!!
BC
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by VetteNoob
So you dont think the 12.1 at the upper rpm range should be closer to 12.5 or 12.6?
Mine was in the mid 11's... so WOT tuning made a worthy improvement.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Mike
The cost of fuel these days, just fine tuning the AF Ratios at cruising speeds to get it back to the 28-30 MPG that it use to get will pay for the software in no time! 
I want to play and figure that it cant hurt to get it.
BC
The cost of fuel these days, just fine tuning the AF Ratios at cruising speeds to get it back to the 28-30 MPG that it use to get will pay for the software in no time!
I want to play and figure that it cant hurt to get it.
BC
Team Owner
Joined: Mar 1999
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From: At the beach in little Rhody
Mine is the same. It is my understanding, and I am by no means an expert, that you run about 0.4 richer on the dyno (at least on the Dynojet) so that if you are at around 12.1:1 then on the street you are roughly 12.5:1. I don't think you should tinker with it. There is a couple of good books on this subject and a lot of good information both here and on LS1Tech.com in the tuning sections.
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Originally Posted by VetteNoob
Im trying to learn more about the LS1 engines. Is it normal for a LS1 to read about 12.5 at 1900 rpm and 12.1 at 5800 rpm on a dyno? The avg across the board is 12.3.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Mine is the same. It is my understanding, and I am by no means an expert, that you run about 0.4 richer on the dyno (at least on the Dynojet) so that if you are at around 12.1:1 then on the street you are roughly 12.5:1.
Last edited by Mike Mercury; May 2, 2005 at 10:07 PM.
